Living tissues of plants and animals depend on electrochemical potentials for many of their normal functions. Charged species such as sodium, potassium and calcium ions are nearly omnipresent throughout mammalian bodies and participate in or facilitate numerous important chemical reactions. Disruption of or interference with these reactions may occur due to chemical imbalances caused by environmental factors including the presence of electromagnetic radiation (EMR) sources, such as power lines, electrical equipment and the like. Recently, EMR sources have been implicated in the development of brain tumors, cancer, headaches, malaise, short-term memory loss and childhood leukemia. Both static electric and magnetic fields (collectively, EMF) as well as radiofrequency (RF) radiation have been implicated in these conditions and diseases. Unfortunately, with modern society's increasing reliance on electrical devices such as refrigerators, alarm clocks, microwave ovens, cellular phones, computers and the like, exposure to EMFs has become more consistent and unavoidable.
Notwithstanding efforts by numerous western nations and Japan to regulate exposure by their people to EMFs as well as regulatory efforts adopted by several states in the U.S., there is disagreement as to the significance of the role EMFs play in the development of disease, notably cancer, in humans. A peer-reviewed report appearing in the British journal The Lancet in December 1999 concluded that there was no link between electromagnetic radiation and childhood cancer in clear conflict with a report by James Clark and David Derbyshire in the Jul. 16, 1998 edition of the Daily Mail that indicated studies conducted by British researches found the use of mobile phones could "disrupt parts of the brain in charge of memory and learning" and could "cause a rise in blood pressure and may harm pregnant women." What is not in dispute is that humans in developed nations are exposed to EMFs as part of the modern environment and that the range of effects due to such exposure is not fully understood. Arguably, reduction or elimination of such exposure in the absence of clear understanding is to be desired. To this end, several attempts have been made in the prior art to reduce exposure by humans to various radiation sources. For example, U.S. Pat. No. 5,570,476, issued Nov. 5, 1996 to B. B. Olive discloses a cap of metallized fabric to protect the wearer from an electromagnetic field. U.S. Pat. No. 5,621,188, issued Apr. 15, 1997 to S. C. Lee et al. discloses an electromagnetic shielding medium which can be used on the head. The shielding medium can be composed of any highly conductive metal, such as copper, and is fabricated as a plurality of geometrically shaped objects (spheres) held in contact with each other in a generally hexagonal array. U.S. Pat. No. 5,038,047 issued Aug. 6, 1991 to S. S. Still discloses a hood to protect the head from radiation exposure. U.S. Pat. No. 5,022,099, issued Jun. 11, 1991 to C. A. Walton shows a solid helmet to protect the head from radiation.
Despite the efforts of the prior art, each of these devices fails to provide EMF shielding which is not only effective at shielding the head but also which is lightweight, thus making economical use of material, simple to manufacture, air permeable and supple enough to be worn comfortably under other head gear such as caps, hats or scarves.